"But you have a few names even in Sardis who have not defiled their garments" (Rev 3:4). Under the image of defiled garments, defilements of the soul are properly depicted metaphorically.
Therefore those who have not defiled their garments are those God-fearing servants of God whose minds have no share in heretical teachings, and whose life is not stained by vices.
"And they shall walk with Me in white." This means that they will be counted worthy of great glory, like the guests in the parable who are clothed in wedding garments at the wedding feast of the king's son (Mt 22:11, 12).
Or they will be like the Savior Himself, whose face shone like the sun during the Transfiguration, and whose garments became white as snow (Mt 17:2).
"He who overcomes ... I will not blot out his name from the book of life" (Rev 3:5). That is, salvation and eternal blessedness in the future life will be appointed for him.
The divine decrees concerning human destinies are expressed by this image. God, as the most righteous and all-knowing Judge, records all human deeds. Accordingly, He writes some among those appointed for life and blessedness, and marks others for condemnation.
This symbolic image is used in many places of Scripture (Lk 10:20; Heb 12:23; below, Rev 13:8; 20:12; 21:27).
"And I will confess his name before My Father and before His angels" (Rev 3:5). That is, I will proclaim him before them and acknowledge him as My faithful disciple and follower.